When a person strikes, strums, plucks or otherwise initiates a vibration of the air space within a musical instrument, the sound waves are amplified when the vibration matches the instrument's natural frequency. There may be one or more natural frequencies, and each natural frequency of an instrument is associated with a standing wave pattern by which the air space inside the instrument could vibrate. These natural frequencies are also called the harmonics of an instrument.
An instrument may be forced into vibrating at a harmonic when an interconnected object pushes with one of the instrument's natural frequencies. This is known as acoustic resonance.
Acoustic resonance is dependent on the shape, size and length of the air space within the musical instrument, and on the material from which the instrument is made. The material from which the instrument is made will also affect the instrument's tone.
For example, most brass instruments and mouthpieces today are made from one of five materials: gold plated brass, silver plated brass, plastic, stainless steel and titanium. Gold plating is expensive, but produces a rich, full, dark tone. Silver plating, while cheaper than gold, produces a clearer, brighter tone. Stainless steel and titanium are also expensive materials, but, because brass may absorb vibration, offer tone qualities not available with plated brass. Finally, plastic is affordable, but has a diminished tone quality. Most plastic instrument components are used primarily outdoors, such as when marching.
The resonance and tone of a drum, such as a timpani, is also dependent on the material from which the bowl is made. Timpani bowls are usually made from copper, fiberglass or aluminum. Copper, the most expensive, produces a darker, richer tone that is not achieved with fiberglass or aluminum, which tend to sound tinny and thin.
It is desirable to produce components for musical instruments that are durable and produce desired tone qualities.
It is desirable to produce components for musical instruments that combine tone and resonance qualities of different materials.
It is desirable to develop a method to produce components for musical instruments that integrate two or more materials with distinct resonance qualities.